CHARLTON — When a man clad in fatigues strode into a school assembly at Heritage Elementary School in Charlton Monday afternoon, the students burst into applause and Cecilia Woodruff, 9, whispered excitedly to her friends.

Both Cecilia and her younger brother, Casey, 7, stayed where they were, sitting cross-legged on the gym floor with their classmates until they realized it was OK to run up and give their father a hug. Army Sgt. Charles R. Woodruff handed his daughter a bouquet of bright flowers and gave his son a video game he had wanted.

Sgt. Woodruff returned to the state Sunday from a tour in Afghanistan, where he worked as a standardization officer. He is a crew chief in a Black Hawk helicopter unit and deployed to Iraq for the entire year in 2009. This time his deployment was shorter but no less difficult.

He is based at Camp Edwards at Otis Air Force Base. When he returned to the United States, he spent about a week at Fort Hood in Texas debriefing before heading back to Massachusetts.

He hid out at a Boston hotel Sunday night, fidgeting and watching time pass slowly so he could surprise his children and their classmates on Monday.

"He did tell me he was going to get me a surprise," Ceclia said after the shock wore off. "But I thought it was going to be a gift you couldn't find in America."

The sergeant's wife of 11 years, Karen A. Woodruff, knew her husband's schedule, but the children did not. The last time Sgt. Woodruff saw his family was when he had a four-day pass in August before deployment. He got to spend about two days with his children before heading out.

"It wasn't enough time," he said. "It's never enough time."

The Woodruffs used an app called Tango to keep in touch. It's similar to Skype and they could see one another during conversations, but the children didn't notice that their dad wasn't in Afghanistan the last time they spoke and he wished his daughter a happy birthday.

"She wanted some puzzles and a hamster," Sgt. Woodruff said. "I said no to the hamster."

Then Cecilia told him that most of all she wanted him to come home.

"It was so hard not to tell her," he said before the reunion.

He said a friend had posted a family reunion video, but he only watched about two minutes of it before he had to turn it off and put on his sunglasses to hide his red-rimmed eyes. He wasn't sure he'd keep his emotions in check Monday, either.

He predicted his daughter would cry and his son would hug him, but it was Casey who shed tears of joy and later said he was "so happy."

The Woodruffs were careful. They didn't post any hints on Facebook and worked hard not to tip off the kids. A friend even posted a comment on Sgt. Woodruff's Facebook wall that would have had anyone believing he was still out of the country.

The Woodruff children weren't expecting to see their father walk into a hastily planned school assembly, where the principal, Kathleen Pastore, was talking to them about acts of kindness and compassion. She reminded the children about the buckets in each classroom and how they can write thoughtful notes to thank their classmates for being kind.

"It's called filling the bucket," she said later, adding that the children try to fill the classroom buckets by doing for others.

She introduced Sgt. Woodruff as someone who works every day to fill the buckets of others by his actions, and the room burst into applause. Fourth-graders, who had been let in on the secret, held up handmade signs with letters spelling out "Thank You." Some of the letters were held upside down, only adding to the sweetness.

Cecilia said she's glad her dad's home because things get dull without him.

"It's like boring," she said. "Because he makes my life good."

Casey said he worries when his father is away, and in a quiet moment after the event, the pair sat close to their dad, asking the inevitable question: Do you have to go back?

Sgt. Woodruff doesn't believe he'll be deployed again. He has 21 years, three months and 17 days of service and retirement is closing in. He'll return to his job at Wyman-Gordon in early March and hopes things quickly get back to normal.

"But if duty calls, we respond," he said.

Contact Kim Ring at kring@telegram.com. Follow her on Twitter @kimmring

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